User Agent and Assistive Technology Support Notes

Description

The purpose of this technique is to show how headings in PDF documents
can be marked so that they are recognized by assistive technologies. Headings are marked up using the heading elements (H, H1, H2, ... H6) in the structure tree.
This is typically accomplished by using a tool for authoring PDF.

Heading markup can be used:

to indicate start of main content

to mark up section headings within the main content area

to demarcate different navigational sections, such as top or main
navigation, left or secondary navigation, and footer navigation

to mark up images (containing text) which have the appearance
of headings visually.

Because headings indicate the start of important sections of content,
it is possible for assistive technology users to access the list of
headings and to jump directly to the appropriate heading and begin
reading the content. This ability to "skim" the content through
the headings and go directly to content of interest significantly speeds
interaction for users who would otherwise access the content slowly.

Using the Touchup Reading Order tool

One method of adding headings to PDF documents uses the Touchup Reading
Order tool:

Open the PDF document in Adobe Acrobat Pro

Select Advanced > Accessibility > TouchUp Reading Order...

Click the Show Order Panel button on the TouchUp Reading Order
panel

View the tags in the Show Order panel.

The following image shows a PDF document opened in Adobe Acrobat Pro.
The Tags panel is open, showing heading text "Cooking techniques" tagged
as H1 and "Cooking with oil" tagged as H2. The text "Cooking
with butter" should be tagged as H2 but is not.

To correct the H2 heading, use the TouchUp Reading Order panel as
follows:

Left click and drag a selection box over the content you want to
tag.

Select the Heading 2 tag from the TouchUp Reading Order panel.

The following image shows the PDF document opened in Adobe Acrobat
Pro. The TouchUp Reading Order panel is visible. A selection box appears
around the text "Cooking with butter," and Heading 2 on the
panel is selected.

Finally, click the Show Order Panel button on the TouchUp Reading Order
panel.

The following image shows the PDF document opened in Adobe Acrobat
Pro. The Tags panel is visible, showing that the text "Cooking
with butter" is now tagged as H2.

Using the Order and Tags panels

You can also add or change headings as follows:

Bring up the Order panel.

Access the context menu for the text to be changed or added as
a heading.

Select the correct heading tag for the text.

The following screenshot shows Order panel and the context menu for
the text "Cooking with butter." "Tag as heading 2" is
selected in the context menu.

You can then check that the correct heading is applied by opening
the Tags panel, as shown in the following screenshot.

Use Styles to create heading formats: Heading 1, Heading 2, Heading
3, etc. Make styles progress in a logical manner; e.g., a Heading 2
should come after a Heading 1.

Export to PDF as follows:

From the File menu, select Export as PDF...

The first time you export as PDF, an Options Dialog appears.

Select Tagged PDF, then select Export.

Example 4: Marking up headings using /Hn elements

Headings within PDF documents can be marked up using /Hn elements elements
in the structure tree, where n is numeral 1 through 6 (for
example /H1, /H2, etc.).

The following code fragment illustrates code that is typical for using
the /Hn elements elements to mark content. Note that /H1 has been role-mapped to /Head1 in this example. This is typically accomplished
by an authoring tool.

Related Techniques

Tests

Procedure

For all PDF content that is divided into separate sections, use
one of the following to verify that headings are tagged correctly:

Read the PDF document with a screen reader, listening to hear
that the list of headings is announced correctly.

Using a PDF editor,
make sure the headings are tagged correctly.

Use a tool that is capable of showing the /Headn entries
to open the PDF document and verify that headings are tagged
correctly.

Use a tool that exposes the document through the accessibility
API and verify that the headings are tagged correctly.

Expected Results

#1 is true.

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.